218 APPENDIX F. FISHES. 



and twelve rows on the peduncle of the tail. Thirty-seven scales on the 

 lateral line. 



Syn. — Pomotis brevicejis, B. & G. Proc. Acad. Nat. Sc. Philad. 

 VI, 1853, 309. 



Description. — The abbreviated head constitutes two-sevenths of the 

 entire length, the caudal fin included. Middle of the cranium slightly- 

 depressed. Nostrils nearer to the eye than to the tip of the snout. 

 Eyes of medium size and circular; their diameter is contained four 

 times only in the length of the head from the snout to the base of inser- 

 tion of the opercular flap, which is longer than a diameter of the eye. 

 The mouth is proportionally small ; the posterior extremity of the max- 

 illary not extending as far back as the middle of the pupil. The teeth 

 are slenderer and more conspicuous than in Pomotis longulus. Cheeks 

 covered with scales, but slightly smaller than those on the' opercular, 

 apparatus. The opercular bones have the same general shape as in 

 Pomotis longulus ; but the opercular flap is very much developed, longer 

 than broad, and rounded posteriorly. The structure of this flap is some- 

 what similar to a fin ; slender and simple rays being distinctly visible 

 through the membrane. 



The dorsal fin commences in a line above the base of the opercular 

 flap. Its spinous portion is almost as elevated as the soft one. There 

 are eleven spinous rays, the first and second smallest ; and ten articu- 

 lated or soft ones, occupying a little more than half the space as the 

 spines. The structure of the soft rays and their relative length are 

 much as in Pomotis longulus ; they bifurcate from the middle of their 

 length, and subdivide again upon their extremity. The caudal is sub- 

 crescentic posteriorly, and its angles rounded. It is composed of seven- 

 teen well developed rays, and a few rudimentary ones. The central rays 

 bifurcate three times. The anal fin is composed of nine soft rays, one 

 more than in P. longulus, and three spinous ones ; the second and third 

 almost equal in length. They bifurcate and divide in the same manner 

 as the dorsal. The insertion of the ventrals is immediately behind the 

 base of the pectorals. Their shape is triangular, and when bent back- 

 wards their tip extends to the anterior margin of the anal fin, thus over- 

 lapping the anus, which is situated as in P. longulus, about a quarter 

 of an inch in advance of the anterior margin of the anal fin. The ven- 

 trals are composed of one spinous and five articulated rays, which bifur- 

 cate three times. The insertion of the pectorals is subcrescentic ; the 

 tip of these fins reaches about as far back as do the ventrals. The 

 rays, fourteen in number, (thirteen of them well developed,) are slender 



